Johan H. Jensen, PhD, Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Denmark. Kamilla W. Miskowiak, DMSc, Psychiatric Centre Copenhagen, Rigshospitalet, Denmark. Scot E. Purdon, PhD, Department of Psychiatry, University of Alberta, Canada. Esben M. Flachs, PhD, Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Denmark. Maja S. Worm, MD, Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Denmark. Jane F. Thomsen, PhD, Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Denmark. Nanna H. Eller, DMSc, Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Denmark.
The purpose of this ongoing study is to optimize screening of objective cognitive impairment in patients with long-term work-related stress. We aim to validate and evaluate Danish language versions of the Screen for Cognitive Impairment in Psychiatry (SCIP-D) and the Cognitive Failure Questionnaire for screening of objective cognitive impairment detected by standardized neuropsychological tests in these patients. We also aim to assess the patients’ levels of cognitive functioning as a potential determinant for work status six months later.
Many patients with long-term work-related stress complain that cognitive limitations impede their vocational functioning. Several studies have reported impaired performance on neurocognitive tests in work-related stress (Deligkaris et al., 2014), but self-report cognitive complaints may not accurately reflect neurocognitive impairment (Burmester et al., 2016; Horvat & Tement, 2020). Neuropsychological examination is resource consuming and not employed routinely in many occupational clinics. Currently, there is no validated objective cognitive screener for patients with work-related stress. Considering the potential value of enhancing cognitive skills to promote recovery (Dalgaard et al., 2020; Gavelin et al., 2018), there is a need a to optimize screening of cognitive impairment in this patient group. The performance-based SCIP-D consists of five subtests assessing verbal memory, executive skills, and processing speed with raw scores that can be summed to offer an index of global cognitive impairment. The self-report CFQ is a 25-item global trait measure of subjective cognitive difficulties relevant to patients with work-related stress.
A final sample of 82 patients with work-related stress (ICD-10 codes: F43.2; F43.9; Z56) were enrolled for a 1.5-hour assessment of demographics, objective and subjective cognitive status, and psychosocial functioning in the Department of Occupational & Environmental Medicine at Bispebjerg Hospital, Denmark. All patients were first screened for eligibility by occupational physicians and then assessed by a psychologist. Main eligibility criteria were 18-64 years of age, excess work-related stress symptoms, and no psychiatric illness or substantial somatic disease. Objective measures of cognitive status included the SCIP-D (administration <20 min.) and six standardized neuropsychological tests that tapped into the same cognitive domains. Subjective cognitive status was assessed with the CFQ. Work status was evaluated by telephone at 6-month follow-up. Patients were matched to a pre-existing pool of normative data from 79 healthy controls (C. V. Ott et al., 2016) using a bootstrapping technique with 1000 resamples according to age, sex, and estimated verbal intelligence. Concurrent validity of the SCIP-D and CFQ was assessed by calculation of Pearson’s correlation coefficients between the objective and subjective tools and the scores on the standardized neuropsychological tests. Decision validity was assessed with logistic Receiver-Operating-Characteristic analyses using a cut-score approach to the objective and the subjective test scores to predict impairment detected by the standardized tests. Associations between SCIP-D and CFQ total scores and employment at 6-month follow-up (yes/no) were analyzed preliminary with logistic regression adjusted for demographics and baseline psychosocial functioning, e.g. employment status. In logistic regression analysis, SCIP-D and CFQ total scores were z-score standardized (mean=0, SD=1) to ease interpretation of results.
There were strong correlations between all standardized neuropsychological tests and the SCIP-D (total score: r=0.76, p<0.001). There was no correlation between global objective and subjective cognitive measures (r0.30). The optimal SCIP-D total-score cut was ≤72, which identified 43.2% of the patients with global objective cognitive impairment (AUC=0.84, 95% CI=0.76-0.93, Sensitivity=0.77, Specificity=0.73). Each one-SD increase in the objective SCIP-D total score was associated with a higher odds ratio of 3.04 (adjusted 95% CI=1.04-8.89) for employment at 6-month follow-up relative to full time sick-leave. The subjective CFQ total score was not associated with subsequent work status (p=0.28).
Associations with neuropsychological tests showed good concurrent validity of the objective cognitive screener, SCIP-D, but not the subjective tool, CFQ. The SCIP-D showed superior decision validity to the CFQ using a cut-score approach for correct classification of patients with objective cognitive impairment. These findings are consistent with studies on patients with mood disorders (Jensen et al., 2015; C. V. Ott et al., 2016). Patients performing 1 SD greater on the SCIP-D total score may be about three times as likely to be employed six months later than their fellow participants, whereas self-report cognitive status did not seem to predict subsequent work status. The HC sample size was insufficient to calculate demographically adjusted norm cut-offs for cognitive impairment (C. V. Ott et al., 2021). The large patient sample was a strength of the study (N=82).
The SCIP-D is a valid and feasible cognitive screener to identify objective cognitive impairment and that may also predict employment 6 months later in patients with work-related stress. The SCIP-D offers brief assessment of performance-based cognitive status for administration by experienced non-specialist healthcare providers in occupational clinics and research. Further studies should evaluate interventions to potentially enhance cognitive skills and functional recovery in work-related stress.